Seams like the GB auction used as reference went for a nice amount, over $1000. Is there any premium on barrel length? Is there much of a premium on 1st year or early production? I've always been of the opinion that the Challenger, Huntsman and Targetsman were Woodsman's baby brothers - getting little respect.
Very nice condition for the gun and the box, and no doubt the gun and the box have been together from the beginning. May or may not be the type of box that the OP gun came in, however. The usual box would be a 2 piece with an oak grain looking finish, top and bottom. The box that nice gun is in may be a leftover 2nd Series Woodsman box that it shipped in from Colt. Not unusual following a recent changeover. Bottom line: either a box like the one in the link, or one with an oak grain looking finish, top and bottom, could be correct.
I may be able to add something here. I have a 1950 Challenger (309C) in it's numbered box. The box is brown leather texture (dull finish) top and bottom, the lid is hinged, and the interior is the tan manilla (like kraft paper) with a rampent colt printed with brown ink. I also have several Ser.2 Match Targets and their boxes are brown leather grain (shinny) with green inside and gold Rampent colt.